1. Field of the Invention
This invention relates to heat transfer devices operating as a thermodynamic cycle, and in particular to the thermodynamic cycling of a photonic crystal with coupled resonant defect cavities to implement heat pumps or heat engines.
2. Description of the Related Art
A thermodynamic cycle is a process in which a “working body” (system) undergoes a series of state changes and finally returns to its initial state. The “working body” can be any material (“working fluid”) through which heat Q can be introduced or transmitted through to produce work. In the process of going through this cycle, the system may perform work on its surroundings, thereby acting as a heat engine. A heat engine acts by transferring energy from a heat source to a heat sink and, in the process, converting some of that energy to mechanical work. The cycle may also be reversed. The system may be worked upon by an external force, and in the process, it can transfer thermal energy from a heat source to a heat sink thereby acting as a heat pump. Most heat pumps move heat from a low temperature heat source to a higher temperature heat sink. The heat pump may be configured as a refrigerator to maintain a cold set-point temperature or as a heat pump to maintain a warm set-point temperature. Most heat engines and heat pumps exploit compression and expansion of gases or phase changes to transfer the heat along with the material changes.